The invention relates to the alkylation of hydrocarbons. In one of its aspects, the invention relates to a low inventory alkylation reactor with an internal acid cooler.
Alkylation is a reaction in which an alkyl group is added to an organic molecule. Thus, an isoparaffin can be reacted with an olefin to provide an isoparaffin of higher molecular weight. Industrially, the concept depends on the reaction of C.sub.2 to C.sub.5 olefins with isobutane in the presence of an acidic catalyst to produce a so-called alkylate. This alkylate is a valuable blending component in the manufacture of gasolines due not only to its high octane rating but also to its sensitivity to octane enhancing additives.
Industrial alkylation processes have historically used hydrofluoric or sulfuric acid catalysts under relatively low temperature conditions. Acid strength is preferably maintained at 88 to 94 wt. % by the continuous addition of fresh acid and a continuous withdrawal of spent acid.
One of the major problems associated with the catalytic alkylation of hydrocarbons lies in handling the alkylation catalyst, that is, transporting the catalyst through the various parts of the reaction and recovery system. The problem is particularly aggravated with acid catalysts, such as hydrofluoric acid, sulfur acid, etc., since these materials share inherent drawbacks including environmental and safety concerns, acids consumption, and sludge disposal. Another problem associated with catalytic alkylation lies in dissipating the heat generated during the alkylation reaction so as to avoid overheating and polymerization of the reactants. Therefore, it is always important in alkylation processes to develop safer and more effective ways of handling the alkylation catalysts and reactants.